Prorocentrales

The Prorocentrales are a small order of dinoflagellate algae, found mostly in estuaries. They are distinguished by having their two flagella inserted apically, rather than ventrally as in other groups. One of these extends forward and the other circles its base. There are no flagellar grooves, and the most notable feature of the theca is a suture along the side where the two main plates meet. This peculiar arrangement have led some to consider the Prorocentrales in their own class, the Desmophyceae (desmoflagellates), separately from all the other dinoflagellate groups. However there is some evidence that the Prorocentrales are polyphyletic within the Dinophyceae, and that the same even applies to genera like Prorocentrum .